The present invention relates to glossy, precious-metal preparations for microwave-resistant tableware-decorations, where the tableware is formed of silicate base materials such as porcelain, ceramics, earthenwares or glass.
It is known that in conventional precious-metal decorations on tableware formed of porcelain, glass, earthenwares or ceramics, microwave radiation builds up so high an electrical potential that arc discharges are generated due to the potential difference between the layer of precious metal in the decoration and the cooking space of microwave oven whereby the decoration will be destroyed.
The German Patent No. 36 15 272 describes microwave-resistant tableware made of silicate base compositions and having precious-metal decorations, where the decorations are deposited not as a sheet layer but as screen elements no more than 5 mm in size and spaced apart from one another by at least 0.2 mm. However, such decorations suffer from the drawback that the human eye notices the screen effect and that accordingly no uniform, area decoration is possible.
The German Auslegeschrift No. 14 21 865 which has basis in U.S. Pat. No. 3,266,912, discloses glossy precious-metal preparations formed of an organic precious-metal compound, a soluble fluxing agent in the form of organic base-metal compounds, and an organic carrier. The fluxing agents are organo-metal compounds in the ratio of 0.3 to 3 moles of base metal per mole of precious metal. Such preparations are used to deposit films containing precious metals on glass-ceramic objects. However no information is provided about decorations that might be microwave-resistant.